In the world of commerce and industry millions of tons of goods and product are manufactured, shipped and stored on a daily basis. As a practical matter a system and method for moving and storing goods and product has evolved over the years. This system generally utilizes a square or rectangular shaped unit called a pallet which lends strength, stability and uniformity to the load which is placed on the pallet.
It has been suggested that the original pallets were not the product of engineering but rather a practical solution of shippers and handlers who realized it was easier to move a load if there was a convenient method to get their tools under it. The first pallets were simply wooden blocks arranged under a load connected to a slat-like board. With the advent of the forklift the pallet eventually became changed to the wooden block and slat structure we see today on a routine basis.
Several factors are considered in designing and constructing a transportable load beating article. The primary factor of course being the capacity of the article to carry the designed load. Another factor is the unladen weight of the pallet. It must be lightweight so that it might be moved and handled without the necessity of special tools or equipment. Stability is another requirement of a load bearing device. The design must be such that the load will remain undisturbed even if the pallet is acted on by relatively strong vertical and horizontal forces. These forces include normal and expected forces routinely found in the moving and shipping trade as well as the accidental and abusive forces that occur as well.
The pallet must be capable of withstanding a masonable variety of weather and still maintain its structural integrity.
Since pallets are shipped to and from locations world wide, they are generally considered expendable by manufacturers and shippers and are, therefore, not returned to their point of origin. A system for identifying and shipping pallets would cost prohibitive. In some areas of the world wooden pallets are disassembled and used for firewood or as building materials. In other areas they are simply considered waste and discarded.
Wooden pallets have the specific potential disadvantage of being capable of damaging the surface either of the load or the surface where the pallet is set to rest. This occurs because of the generally rough surface of the wood or the protrusion of nails caused by poor quality workmanship during manufacture. Likewise wooden pallets have the undesirable propensity of absorbing moisture from the atmosphere and when transporting products, such as paper for example, a layer of material must be placed between the load and the paper to avoid moisture damage. Wooden pallets are heavy to pick up, cumbersome to handle and expensive to make. In an effort to overcome the disadvantages of the prior art pallets constructed of other materials such as fiberboard or corrugated cardboard were developed.
As a general rule corrugated cardboard pallets are strong, lightweight and easily disposed of or recycled. Pallets of corrugated paper are known in the art and have been commercially available for a number of years. A review of the following U.S. Pat. Nos. would establish their place in the world of commerce and industry. U.S. Pat. Nos.
2,728,545 issued to Hermitage on Dec. 27, 1955 PA1 3,683,822 issued to Roberts et al on Aug. 15, 1972 PA1 4,831,938 issued to Atterlay et al on May 23, 1989 PA1 4,875,419 issued to Helton et al on Oct. 24, 1984 PA1 5,001,991 issued to Smith on Mar. 26, 1991 PA1 5,129,329 issued to Clasen on Jul. 14, 1992
The pallet formed of corrugated cardboard has, as a general rule, copied the basic size, shape and design of the wooden pallet. The corrugated pallet exhibits a pronounced advantage over wood in its strength-to-weight ratio. The cardboard being 4 to 5 times lighter than its wooden counterpart. The corrugated pallet cost is only a fraction of the wooden pallet cost. In addition the surface of the cardboard pallet is smoother, finer, and without staples or nails to damage any load or storage surface where the pallet might be placed.
Corrugated cardboard pallets are generally formed of a number of structural pieces which are constructed by scoring and folding a cardboard blank. The folding usually ends with the structural piece encased in a final wrap of the blank material. The U.S. Patent to Schmidtke U.S. Pat. No. 4,792,325 dated Dec. 20, 1988, is example of a method and apparatus for manufacturing cardboard pallets.
A disadvantage to the existing design of cardboard pallets is that it does not perform well when supporting loads on conveyors. If the conveyor is straight complaints are minimal. However, if a conveyor is curved the cardboard pallet tends to jam, causing time delay and inconvenience. By the same token, many cardboard pallets have no means for lifting if the pallet becomes reoriented on a conveyor. The areas designed for lifting may easily become rotated so that at the end of the conveyor the openings for a forklift, for example, are transverse to the tines of the lift.
These and other objections to the corrugated cardboard pallet have caused the invention of the transporter runner.